The Relationship Between Early-Phase Substance-Use Trajectories and Drug Court Outcomes

Abstract

This study sought to identify patterns of substance use among 1,019 participants of the New South Wales Drug Court program (Sydney, Australia) between 2003 and 2009. Group-based trajectory modeling identified five groups of participants: compliant participants (24.4%), who had a near-zero probability of returning a positive urine test at each occasion; responding participants (25.3%), for whom the probability of returning a positive test decreased; relapsing participants (14.1%), for whom the probability of returning a positive test increased; mid-level chronic participants (26.0%), who had a one in two chance of returning a positive test at each episode; and a high-level chronic group (10.2%), who had a very high probability of returning a positive test at each episode. Group membership probability was found to be a good predictor of treatment and criminal justice outcomes. The challenge for future research is to identify the characteristics that explain these early-phase substance use trajectories.